Field of the Invention
The present invention relates to a lens control device, a lens control method, and a recording medium.
Description of the Related Art
In recent years, autofocus (AF) functions of controlling focus lenses so that subjects are automatically focused in imaging apparatuses capturing still images or moving images have been invented. However, depending on imaging conditions in which autofocus functions are used, lenses may be controlled at focus positions unintended by users in some cases. For example, in platform type cameras or the like including camera cases, waste or droplets attached to glass of the camera cases may be in focus in some cases. When figure skating or the like is imaged, the audience in the back may be in focus instead of the skater in some cases.
Methods of controlling focus lenses solely in ranges in which subjects desired to be focused by users are located in the foregoing events have been proposed. In Japanese Patent Laid-Open No. 2009-15147, a switch that transitions to a mode in which a focus drivable range is set is provided and a range in which a focus lens is moved while the switch is turned on is decided as the focus drivable range. Accordingly, an imaging apparatus enabling autofocus to be performed in any focus drivable range desired by a user is disclosed.
In Japanese Patent Laid-Open No. 2006-106356, limit control is performed on an autofocus operation on a near side from a focus limit position stored and set in advance. Further, Japanese Patent Laid-Open No. 2006-106356 discloses an imaging apparatus capable of focusing a subject out of a limit range by not performing the limit control at the time of manual focus.
In the technologies of the related art, when position information regarding focus lenses can be acquired as absolute positions, control (focus limit control) can be realized such that driving ranges of the focus lenses are limited. However, in cases of lens interchangeable imaging apparatuses, position information regarding focus lenses may not be acquired as absolute positions depending on mounted lenses, and there are lenses for which the position information can be acquired only at relative positions at which some pulses are moved from current positions in lens communication. In such lenses, relative position information may not be updated and current lens positions may be unknown when focus rings are manually manipulated. An error may occur between the number of actually driven pulses and the number of pulses maintained as the relative position information whenever a focus manipulation is repeated. Further, for the relative position information, there are also lenses in which updating of position information is stopped at the time of arrival at near end or far end and lenses in which the position information continues increasing or decreasing infinitely.
In the control methods of the related art, it is difficult to perform focus limit control described above on such lenses. For this reason, lens control may be performed at focus positions unintended by users depending on imaging condition in which autofocus function is used.